Influence of placental mannose/N-acetyl glucosamine-binding proteins on the interaction of insulin and insulin-like growth factors with their receptors

• Published in: Biochemistry (Moscow) 2011-09, Vol.76 (9), p.1003-1008
• Main Authors: Nedić, O., Filimonović, D., Miković, Z., Masnikosa, R.
• Format: Article
• Language: English
• Subjects: Analysis; Binding proteins; Biochemistry; Biomedical and Life Sciences; Biomedicine; Bioorganic Chemistry; Chemical properties; Female; Glutathione - analogs & derivatives; Glutathione - metabolism; Growth factors; Humans; Insulin; Insulin - chemistry; Insulin - metabolism; Insulin-Like Growth Factor I - chemistry; Insulin-Like Growth Factor I - metabolism; Insulin-Like Growth Factor II - chemistry; Insulin-Like Growth Factor II - metabolism; Insulin-like growth factors; Kinetics; Lectins; Lectins - chemistry; Lectins - metabolism; Life Sciences; Mannose-Binding Lectin - chemistry; Mannose-Binding Lectin - metabolism; Microbiology; Placenta - chemistry; Placenta - metabolism; Pregnancy; Protein Binding; Proteins; Receptor, IGF Type 1 - chemistry; Receptor, IGF Type 1 - metabolism; Receptor, IGF Type 2 - chemistry; Receptor, IGF Type 2 - metabolism; Receptor, Insulin - chemistry; Receptor, Insulin - metabolism; Sugar
• ISSN: 0006-2979; 1608-3040
• DOI: 10.1134/S0006297911090033

Placenta is a source of carbohydrate-binding proteins that function as molecular scavengers, but they could also be involved in interactions that assist in metabolic control. Mannose/N-acetyl-glucosamine (Man/GlcNAc)-binding proteins from placenta were isolated and their reactivity towards placental insulin and insulin-like growth factor receptors (IR and IGF-Rs) was analyzed. The lectins reduced the binding of insulin and IGF-I in a dose-dependent manner, while almost no effect was observed on the binding of IGF-II. The shape of the inhibition curves changed, suggesting altered binding specificity. The presence of sugar could not reverse completely the effect of the lectins, implicating both lectin-sugar and protein-protein conformational recognition. Since biological molecules in our experimental system were those that are in close relation in vivo , placental Man/GlcNAc-specific lectins may be regarded as potential allosteric modulators of lig- and-receptor interactions in a system of homologous ligands, selectively affecting only binding to tyrosine kinase type receptors (IR and IGF-1R).